1. Field of the Invention
The invention relates generally to apparatuses and methods for measuring the fluid transportation and/or absorption behavior by samples of particulates.
2. Description of Related Art
The desirability and performance characteristics of numerous particulate matter depend in large part on their fluid-transportation and/or absorption behavior. For example, products comprising particulate matter are often evaluated by their ability to absorb water and fluids containing liquid water. Such products include, for example, cat litter, silica gel packs, bentonite, disposable diapers and the like. The particulates may be comprised of organic materials such various forms of cellulose and/or include inorganic materials such as various forms of clays and other ceramics.
There are presently several methods and apparatus for determining the fluid-transportation properties of materials. For example, U.S. Pat. No. 5,138,870 to Lyssy describes an apparatus for measuring the water vapor permeability of porous sheet materials under adjustable constant measuring conditions. As another example, U.S. Pat. No. 4,357,827 to McConnell describes a gravimetric absorbency tester that determines the wicking properties of a material by determining the weight of liquid flowing to or from a test site. The apparatus includes a vessel for containing liquid supported solely by a balance, an indicator for indicating the weight sensed by the balance, a test surface containing the test site on which a specimen or test sample to be tested may received, a conduit operatively connecting the vessel to the test site for directing a flow of liquid between the vessel and test site, and an adjuster for vertically positioning the test site. The surface of the liquid in the vessel is maintained at a constant elevation as liquid flows into and out of the vessel.
One problematic issue associated with generally all liquid absorption testing involves the interface through which liquid is introduced into a specimen or test sample. For example, when the technology described in U.S. Pat. No. 4,357,827 to McConnell is used, a test specimen or sample is placed on a test plate having a hole though which liquid may be directed in an upward direction toward the specimen or sample. Such technology is problematic for testing particulate matter because particulates may fall through the test plate hole, interfere with fluid flow through the hole, and make it difficult to clean the testing plate when the particulates are lodged in the hole. In addition, a means may be required to provide sufficient activation energy to induce the liquid from the hole to wet the sheet and to initiate liquid absorption by the sheet. Such means may, for example, include a pinch valve, that allows liquid to be forced through the hole at a velocity that overcomes surface forces against wetting. Such means may compromise tests designed to measure the intrinsic absorption properties of the test sheet.
To overcome the problems associated with interface problems associated with porous sheet materials, U.S. patent application Ser. No. 12/147,637 to Kallmes, entitled “Fluid Transportation by a Porous sheet of Material,” filed on Jun. 27, 2008, describes apparatuses and methods for transporting fluid to a porous sheet of material. The patent application describes various technical solutions to interface problems associated with the use of porous media to test sheet materials. However, the technical challenges associated with absorption testing for sheet specimen are distinct from the challenges associated with absorption testing for particulate samples.
Accordingly, there exist opportunities to provide alternatives and improvements to known methods and apparatuses for determining the fluid-transportation properties of particulate materials, particularly for the purpose of overcoming any shortcomings associated with known methods and apparatuses. In particular, it has been discovered that the technology described in U.S. application Ser. No. 12/147,637 may be altered and adapted to measure fluid-transporting properties and/or fluid absorption behavior for particulate samples.